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Full text of "Text Book Of Mechanical Engineering"

Tension Stress-Action.

395

Kind of Stress.

Some Cases.

I. Tension

2.  Compression ...

3.  Shear     ......

4.  Torsion (momenta! shear)

5.  Bearing............

6.  Bending (momenta! com-

pression and tension),..

7.  Bending + Tension

8.  Bending + Compression

9.  Torsion + Bending

i o.  Torsion -f Compression...

I Lifting rods, chains, bolts, ropes, boiler shells,
pipes and cylinders, boiler stays, flywheel

All short pillars.                                  Oims-

Punching and shearing, rivets,   pins, cotters,
coupling bolts, keys.

Short shafts, spiral springs.

Plate edges on rivets, cotter edges, and canti-
levers.

Beams, axles, boiler end plates, slide bars, teeth
of wheels.

Crane hooks.

Long pillars, boiler flues, ships' davits, con-
necting rods.

Long shafts, crank arms.
' Propeller shafts.

Tension Stress-Action.—Unit stress x area of section
will give total stress. Therefore :—

Load    =    Total stress.
W       -   ft a.

In the case of steam or water pressure the load is unit pressure x
area pressed upon, and

/tons x area of boiler end, or piston, in square ins. =/t a.

Of course/t may be either * breaking' or 'safe,' and W or p will
vary in like manner.

Example l.~Find safe load for following sections, at 5 tons per
•square inch, (i) 3 ins. dia, (2) 3 ins. dia. with f" cotterway. (3)
3" tube with 2" hole. (Eng. Exam., 1892.)

(1)    a--.

(2)     *-<

(3)   «-<

U

2$

5.5
14

; tons.

W

=24*10 tons.

«/gg» 19*64tons.

EE